Cabbage Lipid Transfer Protein Bra o 3 is a Major Allergen Responsible for Cross-Reactivity between Plant Foods and Pollens

Abstract

RATIONALE: Food IgE-mediated allergy to members of the Brassicaceae family has been increasingly reported. However, cabbage - Brassica oleracea var. capitata -allergy has not been properly characterized. METHODS: A prospective study was carried out, recruiting 17 cabbage allergic patients. Skin prick tests (SPT), specific IgE determinations and double-blind placebo-controlled food challenges (DBPCFC) were performed. A major allergen was isolated from a cabbage extract by RP-HPLC and characterized by N-terminal amino acid sequence and MALDI analysis. CAP-inhibition and immunoblot assays were also carried out. RESULTS: SPT and specific IgE were positive to cabbage in all patients. Five of them referred anaphylactic reactions when eating cabbage, and in other 5 patients cabbage allergy was further confirmed by DBPCFC. Most of them showed associated sensitizations to mugwort pollen and plant foods such as mustard and peach. A 9 kDa cabbage IgE-binding protein, Bra o 3, was purified and identified as a lipid transfer protein (LTP) according to its N-terminal sequence (50% of identity to peach LTP Pru p 3) and molecular size. Interestingly, SPT with Bra o 3 showed positive results in 10/12 cases (83%), thus being a major allergen. On CAP inhibition assays, Bra o 3 managed to inhibit as much as 70% of the total IgE binding to cabbage, 73% to broccoli, 61% to mugwort pollen, and 32% to peach. Both Bra o 3 and Pru p 3 were recognized by IgE from our patients' sera. CONCLUSIONS: Bra o 3, a cabbage LTP, is a major allergen cross-reacting with mugwort pollen and other plant foods.